I agree that mining & relay policy, and a lack of conflicts against that is a good metric (though trivially DoSable by a bad actor who wants to mine one weird tx).
Noting that while features like CTV or CAT can be emulated with a signer, block level introspections like transaction sponsors or must-use outputs cannot be emulated using signing federations.
On the whole, I just don’t expect hat an opcode that stops working after a delay would be convincing for people to use more than a token amount of funds for… might work well for things like lightning channels where expecting to close w/in 3 years is reasonable, less good for vaults.